Was Jon Huntsman campaigning while he was still ambassador?

In Jon Huntsman's final weeks as ambassador to China, he stressed that he would not decide whether to run for president until he returned to the United States -- an important statement, because sitting ambassadors are prohibited from actively taking part in political campaigns.

But while still heading the U.S. Embassy in Beijing, Huntsman accepted invitations to deliver commencement addresses in the pivotal nominating states of New Hampshire and South Carolina. In New Hampshire, two political operatives who are now playing key roles in his soon-to-be-announced presidential bid helped arrange his visit.

Both were connected to a team of Republicans who assembled a robust campaign-in-waiting while Huntsman was ambassador, making liberal use of a Utah-based political action committee. Huntsman says he had no contact with the group until he resigned from his post.

But because of their work, he had a sophisticated political operation ready the moment he got home in late April, allowing him to quickly escalate to the full-blown campaign he is set to unveil Tuesday with his formal candidacy announcement.

Huntsman's decision to remain ambassador while his allies assembled a political infrastructure on his behalf raised serious concerns among some experts in ethics and government service. The Hatch Act places limits on partisan political activity by federal employees, including politically appointed ambassadors.

In an interview, Huntsman insisted that he had no relationship with the strategists working on his behalf until he left government service and returned from China.

"I couldn't have told you we were going to do this until I got home," he said during a recent stop in Berlin, N.H., adding that he first met the team the day after his return. "I didn't know anybody around the table. They were all brand-new."

"We were overwhelmed, really," said his wife, Mary Kaye. "We had no idea that all the groundwork had been done."

Huntsman did know the key player behind the informal campaign: veteran GOP strategist John Weaver, who began advising him in early 2009 when Huntsman was still governor of Utah.

The effort to pave the way for a Huntsman presidential campaign apparently began in late September 2010, when Weaver and a trio of Huntsman allies -- including Scott Anderson, chief executive of Zions Bank -- set up Horizon PAC, a Utah-based political action committee.

Craig Engle, the committee's general counsel, said it was organized as "a national PAC under the laws of Utah," with the mission of "identifying a new generation of conservative leaders."

Two months later, Huntsman hinted in a Newsweek interview that he was considering a run. On Jan. 31, he submitted his resignation but said he would stay in his ambassador post until April 30.

In the meantime, Horizon PAC hired a national pollster, a communications director and staff in New Hampshire and South Carolina -- a team that is expected to be part of Huntsman's campaign. Exactly how the PAC spent its money is unknown; because of Utah's loose campaign finance disclosure laws, the organization does not need to report its activities until August.

PAC officials made no secret of their affinity for Huntsman. In a mid-March fundraising email seeking donations of $50,000 to $100,000, Anderson wrote that while the ambassador had no current association with the group, "the PAC is ready to assist him if he decides to run for the presidency in 2012 and/or 2016." The email was first reported by Politico.

The committee's activities fueled widespread speculation that Huntsman, still in Beijing, would jump into the race -- a dynamic that some specialists in government ethics said was inappropriate.

"Whether he gave explicit encouragement or not doesn't matter very much," said Paul Light, a professor of public service at New York University. "Ultimately, you have to ask, 'What do the Chinese think when they read newspaper articles that Huntsman may be preparing to challenge Obama? What do they think about the validity of his policy advice?'... The appearance questions that are raised are serious and important."

The buzz about Huntsman's possible candidacy led Southern New Hampshire University President Paul J. LeBlanc to ask him to deliver the commencement speech in May.

LeBlanc said he contacted Huntsman with the help of Peter Spaulding, a prominent Republican who is now Huntsman's top political advisor in the state. After he emailed the invitation to Huntsman's assistant in Beijing, LeBlanc said, Huntsman responded quickly, accepting in early April with "sincere humility," as he wrote LeBlanc.

Two days later, Lanny Wiles, a veteran presidential campaign aide who has known Huntsman for decades and now travels with him, emailed LeBlanc's assistant to begin making the arrangements. Spaulding said he had alerted Wiles that Huntsman had accepted after hearing the news from a member of the university's board of trustees.

It was not clear why the two would have started setting up logistics without some input from Huntsman, but Huntsman spokesman Tim Miller said that Huntsman had no contact with either man while he was ambassador and that the two were essentially anticipating his needs.

Once Huntsman returned home, the former ambassador said he could not believe the extent of the organization that had developed on his behalf.

"To have people believe enough in you or what you have done -- I would have called them all crazy -- 'Why are you doing this? You've got better things to do,' " Huntsman said. "It was a very humbling moment."

Republican ethics officials said ambassadors need to be careful about political activity, but they had differing views on the propriety of Huntsman's actions.

"The Hatch Act makes it clear that you cannot serve two masters," said Richard Painter, who was White House ethics advisor under President George W. Bush. "You either serve the government or you are running for office. The two are incompatible."

"I would have said, 'You have to make up your mind,' " added Painter, who said he was considering supporting either Huntsman or former Massachusetts Gov. Mitt Romney in the campaign. "If there is any significant chance you are going to run, then you have to resign. If not, you have to tell your supporters and any committees that they have to stand down."

Yet John B. Bellinger III, the State Department legal advisor during the Bush administration, said there was no indication Huntsman did anything wrong, and suggested Painter was being overly cautious.

"He stayed in office while others speculated about a possible presidential race," Bellinger said. "That's not inconsistent with the Hatch Act or any of the State Department guidance."